The present invention is directed to a method for the passivation of crystal defects in polycrystalline or amorphous silicon material using a method that includes a heating step in a hydrogen-containing atmosphere.
It is known to use silicon material, such as polycrystalline silicon wafers, silicon layers, and silicon materials of arbitrary shapes, to make electronic components. These materials, however, typically include crystal defects such as, for example, point defects or line defects, and offsets or drain boundaries. These crystal defects result in the electronic components manufactured from such silicon material having a diminished quality. For example, solar cells or photodiodes that are constructed from a silicon material having a crystal defect exhibit diminished photocurrent sensitivities and no-load voltages as a consequence of increased recombination currents. Unfavorable diode properties occur using such silicon materials.
Methods, typically referred to as "grain boundary passivation", have been suggested for reducing the effect of these crystal defects. Examples of such methods for reducing the influences of crystal defects include:
a) Implantation of ionized hydrogen atoms: J. E. Johnson, J. I. Hano Ka, and J. A. Gregory, 18. IEEE Photovoltaic Specialists Conference, Las Vegas 1985, pages 1112-1115;
b) Treatment with a hydrogen plasma: W. Schmidt, K. D. Rasch, and K. Roy: 16. IEEE Photovoltaic Specialists Conference, San Diego, 1982, pages 537-542, U.S. Pat. No. 4,835,006; and
c) Temperature treatment in a hydrogen atmosphere: A. Agarwal, D. Bana, and C. M. Singal: Int. I. Electr. 1985, Vol. 58, No. 5, pages 769-774.